I ride Market St. or 3rd or others with heavy train tracks. I
ride over the local Alameda bridges and they are all steel
gratings. I ride over the steel plates thrown over the top of
excavations. And I've never had a sidewall blowout on a
Gatorskin. Though I have on the less expensive tires.

I'm wondering if you over or under inflate your tires a large
amount.

I inflate to around 105psi and don't let them drop lower than
75psi. A road bike tire is supposed to be able to live with that.

When I started road cycling the nice guy at my LBS who was mentoring
me expressed surprise that I was not yet pumping up my tires every
day, ...

There you can see how much cyclists have gotten used to sub-par gear.
Can you imagine having to pump up the tires of your car every few days?

and then appeared alarmed at my response, and said emphatically
"Below 80 they can roll off in a corner!!!"

They don't. Also, ever since I switched to thick tubes it takes 6-8
weeks to drop to 75psi.

I can't remember rolling a tire off unless the pressure was reduced to near nothing by a flat. I'm sure that you could roll a tubular off at lower pressures so that might be where that myth came from.

I have only done that slowly and as straight as possible. When a side
wall blows out the tube and tire are hosed anyhow so I continue riding
on the flat as long as possible. Pretty much until the tire is about to
wear through where the rim could contact the soil or pavement. Any mile
not walked is time saved for the trip home.

I have only done that slowly and as straight as possible. When a side
wall blows out the tube and tire are hosed anyhow so I continue riding
on the flat as long as possible. Pretty much until the tire is about to
wear through where the rim could contact the soil or pavement. Any mile
not walked is time saved for the trip home.

I got a flat on a gatorskin and discovered my flat pack missing. I don't know if it fell off or was stolen. There was a Performance Bicycle in Dublin that I remembered and rode three or four miles there and replaced the tube etc. and carried on without any visible damage to the sidewalls of the gatorskin.

I have only done that slowly and as straight as possible. When a
side wall blows out the tube and tire are hosed anyhow so I
continue riding on the flat as long as possible. Pretty much until
the tire is about to wear through where the rim could contact the
soil or pavement. Any mile not walked is time saved for the trip
home.

I got a flat on a gatorskin and discovered my flat pack missing. I
don't know if it fell off or was stolen.

No, no, you sent them to me :-)

... There was a Performance
Bicycle in Dublin that I remembered and rode three or four miles
there and replaced the tube etc. and carried on without any visible
damage to the sidewalls of the gatorskin.

Then you were lucky. Mine were unfixable, it looks like someone fired a
45 through it from the other side.